Force field influences in beta-hairpin folding simulations

Area of Science:

• Computational chemistry
• Biophysics
• Molecular dynamics

Background:

• All-atom force fields are crucial for understanding protein folding mechanisms.
• Current force fields face challenges in accurate implicit solvation and backbone interactions, potentially leading to biased structural distributions.
• Evaluating and refining these force fields is essential for reliable protein simulations.

Purpose of the Study:

• To investigate the performance of recently improved AMBER backbone interaction schemes for beta-hairpin peptide folding simulations.
• To analyze the influence of different force fields on peptide folding mechanisms.
• To assess the suitability of implicit solvation models for secondary structure studies.

Main Methods:

• Utilized replica exchange molecular dynamics for efficient conformational sampling.
• Employed implicit Poisson-Boltzmann solvent for large-scale simulations, validated against TIP3P explicit solvent.
• Tested several AMBER force fields, focusing on ff03 and a revised ff99, for beta-hairpin folding simulations.

Main Results:

• The ff03 and revised ff99 AMBER force fields demonstrated comparable agreement with experimental structural and thermodynamic data.
• Simulations revealed distinct folding pathways, including the order of hydrogen bond zipping and the presence of intermediate states, between the tested force fields.
• The implicit Poisson-Boltzmann solvent proved reasonable for secondary structure studies.

Conclusions:

• Force field choice significantly impacts the predicted folding mechanisms of peptides.
• While ff03 and revised ff99 offer good overall agreement with experiments, their detailed mechanistic predictions differ.
• Further refinement of force fields is necessary for accurate and consistent representation of protein folding dynamics.